Why does Emission shader dilute colors? EEVEE
added a comment but I think it's an complete answer.
So, here's what you can do.
Turn off bloom settings in eevee and use emmision strength of just 1.
Now,render the thing. After that,go into the compositing tab and click on use nodes. Add in a flare node just before output node. Now you can use bloom effect without changing the mesh's colour.
You can watch this video if you had any problem using glare node-
https://youtu.be/SN8nJXn7CqI